Mandrels for use in the production of tubes



July 1, 1969 JQNES 3,452,584

MANDRELS FOR USE IN THE PRODUCTIQN OF TUBES Filed Dec. 23, 1966 UnitedStates Patent US. Cl. 72-466 2 Claims ABSTRACT OF THE DISCLOSURE Acombination of a readily engageable and disengageable mandrel and plugmade up of a mandrel, and an adaptor on the end of the mandrel whichadaptor has a shoulder portion and a frustoconical spigot projectingfrom the shoulder portion. The spigot has a longitudinal tranverse slotwhich carries a resilient plate. The plate has a pair of spaced limbsdirected towards the free end of the spigot, and each limb has anoutwardly projecting portion at its end which projects beyond thesurface of the spigot. A plug is fitted onto the spigot and has a socketfor receiving the spigot and an enlarged cavity in which the projectionson the ends of the limbs are received. The plug, when mounted, bearsagainst the shoulder on the adaptor.

This invention relates to mandrels for use in the production of tubes bya process in which a heated billet is formed into a tube by beinghelically fed onto a plug, carried on the end of a mandrel, by means ofrolls driven on skew axes.

The plug is required to withstand considerable heat and rubbing pressureand it has been found that the life of a plug can be extended bychanging plugs for each new billet. In this way the used plugs can becooled, as required before reuse.

It is thus necessary to provide some readily engageable anddisengageable means for retaining the plug on the mandrel. The plugretaining means should be such that the plug can be removed by a simplepulling action and replaced by a pushing action. At the same time theplug must be held in place so that it does not drop from the end of themandrel inadvertently.

In accordance with the invention there is provided the combination of amandrel an adaptor on the end of the mandrel, which adaptor has ashoulder portion and a frustoconical spigot projecting from the shoulderportion, the spigot has a longitudinal transverse slot which in turn hasa resilient plate mounted in it. The plate has a pair of spaced limbsdirected toward the free end of the spigot, there being outwardlyprojecting portions at the ends of the limbs which project from thesurface of the spigot. Finally, a plug is fitted on the spigot and has asocket for receiving the spigot and has an enlarged cavity in which theprojections on the ends of the limbs are received. The plug bearsagainst the shoulder on the adaptor.

Reference will now be made to the accompanying drawing in which FIGURES1 and 2 are mutual perpendicular sectional views showing one example ofthe invention taken along section lines I-I, I=III, respectively.

Referring to the drawings it is desired to mount a plug on the end of amandrel 11. To this end the plug 10 is formed with a socket constitutedby a recess 10 tapering from an annular end face 10 to a constrictedthroat 10. Beyond the throat 10 the recess is enlarged to form a cavity10 Provided on the mandrel 11 is an adaptor 12 formed with afrusto-conical spigot 13 adapted to fit in the tapering portion of therecess 10 so that the face 10 of the plug 10 can abut against a shoulder14 on the adaptor. Formed in the spigot 13 is a transverse slot 13 whichextends from the shoulder 14 up to the free end of the spigot 13.

Mounted within the slot 13 is a resilient plate 15 of generally U-shapedform. The two limbs 15 of plate 15 are directed towards the free end ofthe spigot 13 and the plate is held in position by a peg or screw 16extending across the slot 13 through a hole in the plate 15 adjacent theshoulder 14. Adjacent the free end of the spigot 13 a roller 17 ismounted between the limbs 15 to keep these properly orientated.

As shown the limbs 15 do not project from the surface of the spigot 13except at their free ends where there is a projecting portion 15 on eachlimb. At each end of each portion 15 there is an inclined cam surface.

Thus, in use, the plate 15 collapses resiliently when the plug 10 ispushed on or pulled off the spigot. It provides, however, a sufiicientlysecure connection to prevent inadverent separation of the plug from themandrel. This is of some importance in a three-roll piercing machine,where premature separation of the plug from the mandrel may result inseveer damage to the rolls.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. In combination a mandrel; an adaptor on the end of said mandrel, saidadaptor having a shoulder portion; a. frustoconical spigot projectingfrom said shoulder portion, said spigot having a longitudinallyextending transverse slot; a resilient plate mounted in said slot andhaving a pair of spaced limbs directed toward the free end of saidspigot and outwardly projecting portions at the etnds of said limbsprojecting from the frustoconical surface of said spigot; and a plugfitted on said spigot, which plug has a socket to receive said spigotand an enlarged cavity in which said projections on the ends of saidlimbs are frictionally received, the plug bearing against said shoulderon the adaptor.

2. The combination claimed in claim 1 in which said resilient plate isof U-shaped configuration and in which there is provided a pin passingthrough said spigot and said plate adjacent said shoulder, and a rollermounted in said slot adjacent the free end of said spigot to retain saidplate in the proper orientation.

References Cited UNITED STATES PATENTS 1,989,507 1/1935 Diescher 72-2082,167,424 7/1939 Novack 72-209 2,257,979 10/1941 Rubinstein 287-124FOREIGN PATENTS 987,512 3/1965 Great 7 Britain.

CHARLES W. LANHAM, Primary Examiner. l

A. RUDERMAN, Assistant Examiner.

US. Cl. X.R.

